Hydraulic apparatus



Aug. 30, 1966 H. GAENGER 3,269,123

HYDRAUL I C APPARATUS Filed July 10, 1964 4 Sheets-Sheet l & m

Jnven/or: HANS GAENGEIZ Qw-MZ.

Aug. 30, 1966 H. GAENGER 3,269,123

HYDRAULIC APPARATUS Filed July 10, 1964 4 Sheets-Sheet B Jnven/or: HA NS GAENG'ER mam/4%;

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Aug. 30, 1966 H. GAENGER HYDRAULIC APPARATUS 4 Sheets-Sheet 4 Filed July 10, 1964 Jnven/ar:

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@Yr-Z United States Patent 3,269,123 HYDRAULIC APPARATUS Hans Gaenger, Upper Bavaria, Germany, assignor to Carl Deschamps, trading as Delhydraulik Altenerding Dipl. Eng. Carl Deschamps, Upper Bavaria, Germany Filed July 10, 1964, Ser. No. 381,645 1 Claim. (Cl. 60-5415) This invention relates to hydraulic apparatus of the kind comprising a housing having a hydraulic fluid reservoir and a bore which accommodates a pump piston for feeding hydraulic fluid under pressure to a working cylinder or working cylinders, a control member being mounted on the housing for controlling the pressure of the hydraulic fluid.

In hydraulic devices having several working cylinders in which high pressures occur and a frequent change from pressure to a pressureless state is necessary, difiiculties are encountered in producing and maintaining the required pressure level of the hydraulic medium for a required operation. Even with most careful developing of the seals between the moving parts of the working cylinders and the control member it is very difficult to avoid leakage losses or the inclusion of air cushions in the long run. This has been taken into account in known arrangements by the feature the necessary quantity of working medium e.g. oil can be supplied from a reservoir to the working cylinders as required by means of a pump. The recharging operation however necessitates an additional operation which in most cases is elfected by the operative who also actuates the control member.

For reasons of structural simplification, the more advantageous accommodation and facilitated handling it has been proposed to combine the control member, the reservoir and the pump structurally in apparatus of the kind referred to. The devices constructed according to this proposal however still have certain deficiencies. As has been established they do not sufficiently take into account the practical requirements. Thus, e.g. possibly by means of a manually actuated pumping operation to increase the pressure of the working medium to the desired extent. In apparatus wherein the working medium is subjected to the constant change between pressure and pressureless state, it is possible if very high pressures occur, for the screw connection between the housing of the control member and the housing of the pump to become loose, which then results in an undesired pressure drop.

According to the invention hydraulic apparatus comprises a housing having an hydraulic fluid reservoir and bores which accommodate a control piston and a pump piston, the pistons being operatively connected, the pump piston bore communicating with the reservoir through a suction valve and, independently of the suction valve, through a stop valve, at least one pump piston bore outlet being provided for connection to a working cylinder.

Hence it is obtained that simultaneously with the control operation a pumping operation is also brought about, by means of which only then the working cylinders are recharged or topped up when the stop valve is actuated. By means of the connection between control member and pump it is possible to ensure that only a quite definite pressure is produced by the pump. A piston slider known per se is preferably used as basis to act as control member, the cylindrical control piston of which at its free end is constructed as pump piston, the bore for which accommodates the control piston and with its closed end forms the pump cylinder.

The stop valve has to be actuated when the control piston is merely to fulfill its control function, thus when the hydraulic working medium has been brought to its predetermined pressure for the hydraulic system. To

actuate this stop valve an additional operation is necessary, which may be omitted if the stop valve is an automatic safety valve set to the predetermined maximum permissible value of pre-loading of the working medium. The safety stop valve automatically renders ineffective the pumping operation occurring with each movement of the control member, as soon as the predetermined pressure of the working medium has been exceeded.

The invention will be further described, by way of ex ample, with reference to the accompanying drawings showing hydraulic apparatus according to the invention and which is intended to support a jointed cross shaft axle of a cross-country vehicle, such as a mechanical excavator, mechanical crane or the like, and in which:

FIG. 1 is a section through an hydraulic control device on the line I-I of FIG. 2.

FIG. 2 is a part sectional plan of the device on the line 11-11 of FIG. 1

FIG. 3 is a flow diagram of the hydraulic apparatus and,

FIGS. 4 and 5 are fragmentary sections, to be regarded as taken on the line 1-1 of FIG. 2, of two embodiments of an automatically acting stop valve.

In the description below of the drawings the apparatus is described and further features and also advantages connected with the invention are discussed.

The apparatus in accordance with the invention, as evident from FIG. 3, comprises an expediently centrally arranged control member 1 of a hydraulic apparatus for supporting a jointed cross shaft axle, not shown in detail, for example a cross-country mechanical excavator. Such jointed cross shaft axles as known have as object to enable the excavator to adapt itself to the unevenesses of the ground to be traveled over. It is necessary however that they form a rigid unit with the chassis during excavating. For this purpose the chassis of the excavator, the so-called undercarriage, has provided thereon for each jointed cross shaft two hydraulic working cylinders 2 and 3 which with the free rounded ends of their connecting rods 4 and 5 are mounted on corresponding supporting surfaces 6 and 7 of the jointed cross shaft. By means of pipe lines 8 and 9 the cylinders 2 and 3 communicate with the control member 1, by means of the actual control part thereof an hydraulic connection between pressure spaces of the cylinders 2 and 3 can be brought about. The control part is pneumatically actuated by operation of an air valve 10, by means of which compressed air is supplied from the compressor 11 of the excavator via the air pipe 12 to the air working control cylinders 13 of the control member 1.

The control member 1 in accordance with the invention as shown in FIGS. 1 and 2, comprises a substantially rectangular housing block 14, which at its cover surface 15 is provided with a cylindrical extension 16 and on its end face 17 with a screw extension 18. Slipped over the cylindrical extension 16 is a tube section 19 with sealing fit, which at one of its ends is closed tightly by a cover 20, which by means of two axially extending screws 21 is firmly clamped against the housing block 14 and has a central charging opening closed by means of a filler screw cap 22.

The tube section 19 closed by the cover 20 and slipped over the extension 16 causes a pressuretight reservoir for recharging working medium, in the present case pressure oil, to be formed. This reservoir communicates by means of a central blind bore 23 of the housing block 14 with a bore 24 of the housing block 14 issuing horizontally centrally in the screw extension 13. In the mouth of the blind bore 23 a suction valve 25 is inserted, which is adapted to open in the direction of the closed end of the blind bore 23. The horizontal bore 24 accommodates the control member 26, the front end 27 of which is constructed as pump piston, the central part of which has a transverse bore 28 and the rear end 29, which is preferably stepped, is constructed as piston for the compressed air which together with the cylindrical cap 13 screwed onto the screw extension 18 results in a compressed air working control cylinder. The bore 24 communicates with two co-axial tapped bores 30 and 31, one of which 30 issues into the cover surface 15 and the other 31 into the base surface 32 of the housing block 14. These two tapped bores 30 and 31 serving the connection of the connecting pipes 3, 9 leading to the power cylinders 2, 3, in turn communicate via transverse bores 33, 34 each with tapped bores 36 or 37 issuing at the lateral surface 35 of the housing block 14, the latter tapped bores being closed by means of a screw 38 and containing a check valve 39, which release the flow in the direction of the bore 33 or 34. The two tapped bores 36 and 37 are interconnected by means of a bore 40 at right angles thereto and issuing in the base surface 32 where it is closed, which bore in turn communicates with the blind bore 23 by means of a bore 42 issuing in the lateral surface 35 where it is closed, on the other hand continuing in a tapped bore 43 issuing into the end face 44 in which a valve vent 45 is screwed. The tapped bore 43 communicates by means of a vertically extending bore 46 with the reservoir 19, 20.

Below there is described in detail, proceeding from the functional state shown in the drawings, the method of operation of the apparatus in accordance with the invention and having a manually actuated stop valve. The air cylinder 13 is subjected to air pressure, therefore the air piston part 29 and hence also the whole slider piston 26 assumes its right hand end position, resulting in the separation of the hydraulic connection between the two working cylinders 2 and 3. If these cylinders are subjected to pressure, then the rigid connection between the jointed cross shaft axles and the chassis of the excavator is produced. If the excavator operative wishes to cancel the rigid supporting of the jointed cross shaft axles in order to drive then he merely has to actuate the air valve 10 arranged in the operatives stand so as to cut off the compressed air supply to the cylinder 13 and d e-aerate the pipe 12. The return spring 47 then causes the air piston part 29 and hence the control piston 26 to assume its left hand end position wherein the transverse bore 28 of the control piston registers with the tapped bores 30 and 31, so that via the pipes 8 and 9 the working cylinders 2 and 3 are now hydraulically interconnected, whereby the jointed cross shaft axle supported on the pistons 4 and of these cylinders can swing about its mounting. By suitably dimensioning the transverse bore 28, which may be replaced by an annular groove, it is possible to throttle the overflow of the pressure oil from one cylinder to the other, whereby in simple manner damping of the swinging movement is obtained.

In returning the control piston 26 into the left hand end position, however, results in a subsequent flow of oil from the reservoir 19, 20 via the automatically opening suction valve 25, because the cavity, defined by the front end 27 of the control piston forming a pump piston and by the blind bore 23 and the bore 24 issuing therein, is enlarged. This oil, if the control piston is caused to assume the right hand end position, has to be displaced again. As long as the stop valve 45 is closed, as shown the oil flows via the bores 42, 41, 40 into the bores 36, 37 and from there via the pressure valves 39 into the connecting pipes 8, 9 in which, as also in the cylinders 2, 3, the pressure is lower than in the pump system formed by the above bores. Hence the pressure oil is recharged in the hydraulic power system, whereby either leakage oil losses are compensated or in the installation de-aerated or even the pre-loading of the working medium in the system can be increased in a required manner, in order to improve or maintain the rigidity of the support.

In the known apparatus constructed in accordance with the initially mentioned proposal the recharging pump is to be actuated manually. By means of a certain relationship of length between power and load arm it is to be ensured that with pumps having normal manual power the maximum permissible value for pre-loading of the working medium of the apparatus cannot be exceeded. If however the support of the jointed cross shaft axles of the excavator does not appear to be operative to be rigid enough, and if by normal actuation of the manual pump the pre-loading and hence the rigidity of the support can no longer be increased, then he simply extends the force arm of the hand lever by slipping a pipe or the like thereover in order to continue pumping. This among other things leads to heavy damage to the hydraulic device and deformation of the jointed cross shaft axle.

In the apparatus according to the invention a permissible increase of the pre-load of the working medium is no longer possible. Proceeding from an air pressure of 4 atmospheres conventionally produced by the com-- pressor of the excavator, the pressure surface of the air piston part 29 in relationship to the pump piston part 27 of the control piston 26 is so dimensioned that no increase of the pre-loading of the hydraulic working medium can be obtained by subsequent pumping above a pressure of, for example, 40 atmospheres.

If the control piston 26 merely has to fulfill its controlling function, then by opening the stop valve 45 the pumping operation of the pump piston operatively connects with the control piston is neutralised. The pump part 27 then merely circulates the oil contained in the pump system and the reservoir because, by opening the stop valve 45, a connection is brought about between the reservoir and the bore 41 via the bore 43 and the bore 46 forming a part of the pump system.

The apparatus forming the subject matter of the in-.

vention further developed and improved therewith causes considerable progress relative to the prior art. The combination in accordance with the invention of control member and pump presents the advantage that only a single housing block is necessary wherein all important bearing/mounting and conduit bores form an organic unit. The sealing problems are readily controlled, because only sealings between cylindrical, accurately machinable surfaces are involved. The combined control-pumping piston is a simple turned part.

The invention is not limited to the embodiment shown in the drawings. In place of actuating the control-pumping piston by means of compressed air, it is also possible to eifect the actuation by means of a mechanically acting rod mechanism or by electrical means e.g. by means of a magnet. The constructional development of such actuations is within the range of expert knowledge. Compressed air actuation however is particularly expedient in the case of mechanical excavators or other cross-country vehicles, because these are in any case equipped with a compressed air generator for actuating the brakes. The supply of compressed air to the actuating device mostly arranged in the proximity of the power cylinder may be passed for the purpose of conduit passage through a king journal of conventionally hollow construction. It is however also possible to pass trough the king journal the electric leads for an actuating magnet or the connecting rod mechanism or cable of a mechanical actuating device.

In the embodiment described the stop valve 45 is shown as a manually actuated screw valve for simplicitys sake. This manual valve may be replaced for example by a pneumatically operated valve which can be operated from the operatives stand of the excavator, where there is also the air valve 10.

In place of the conical valve 45 in FIGS. 1 and 2 of the drawing to be actuated directly or indirectly by hand, according to FIG. 4 an automatically acting safety valve 47 is screwed into the tapped bore 43 issuing at the end face 44 of the housing block 14. This safety valve 47 comprises a housing cap 48 provided with an hexagonal head 49, in the blind bore of the cap are accommodated the valve body 50, closing the longitudinal bore 41 of the housing block 14 with a conical tip 51, and the valve spring 52. In the screwed in state of the safety valve 47 the accordingly dimensioned valve spring 52 has a pre-loading corresponding to the predetermined pressure of the working medium.

In order possibly to vary the pressure of the working medium within certain regions or in order to enable the compensation of the fatigue of the valve spring 52 occurring in the course of time, it is advantageous to use an adjustable safety valve 53 in accordance with FIG. 5 of the drawing. This is distinguished from the safety valve 47 shown in FIG. 4 merely by the fact that its housing has a tubular extension 55 provided with an internal thread into which a threaded spindle 56 is screwed, which with its stepped and bored front end 57 forms the abutment for the valve spring 52; a handle 59 is mounted and on the rear stepped journel 58. Screwing the spindle 56 in or out permits the length of the spring 52, and hence its pre-loading to be varied.

Both safety valves 47 or 53 open automatically as soon as the pressure of the working medium produced by the pump part 27 exceeds the predetermined maximum value. As in the apparatus according to FIG. 5, 1 to 3 (via bore 46) connection is established between the reservoir and the actual hydraulic system and control operations occur only if pistons 26, 27 is actuated.

The range of application of the apparatus in accordance with the invention is not limited either to the supporting device for excavators or other cross-country vehicles shown in the drawing, but extends to all hydraulic devices having working cylinders, the subject of which is to control several, possibly even double construction/ interconnected working cylinders, and to bring about and/or maintain therein the required pressure state of the working medium.

I claim:

Hydraulic apparatus comprising, in combination, a substantially rectangular housing block formed with a vertically extending cylindrical portion (16); and a horizontally extending portion forming a pressure chamber; an oil supply reservoir (19, 20) mounted on said vertically extending cylindrical portion; a cylindrical air motor housing (13) secured to the free end of said horizontally extending portion;

said housing block having a vertical bore (23) terminating as a blind lower portion, and a horizontal bore (24) whose one end communicates with said blind lower portion, the upper end of said vertical bore opening into said oil supply reservoir (19, 20); a suction check valve (25) in said vertical bores upper portion, said suction check valve being adapted to open in the direction of said blind lower portion, for connecting the reservoir and the pressure chamher; a control member (26) slidable in said horizontal bore, said control member including a pressure-producing piston (27) secured to its one end and an air pressure responsive piston (65) secured to its other end, said air-pressure responsive piston being displaceable in said cylindrical air motor housing (13), said control member (26) having a transverse bore (28); said housing block having:

a pair of coaxial output bores (30, 31) communicating with said horizontal bore, one of said coaxial output bores issuing into the top surface, the other of said coaxial outlet bores issuing into the bottom surface of the block, for connecting to a pair of power cylinders, a pair of tapped bores (36, 37) issuing at the lateral surface (35) of the housing block, a pair of transverse bores (33, 34) connecting said coaxial output bores (30, 31) with said tapped bores (36, 37), each of said tapped bores (36, 37) being provided with a check valve (39), for releasing the flow in the direction of the transverse bores (33, 34), a blind bore (40) interconnecting said pair of tapped bores (36, 37) at right angles thereto and issuing into the bottom face of said block, said blind bore (40) being closed thereat, said blind bore (40) comrnunicating with said blind lower portion of said vertical bore (23) and terminating as a tapped end portion (43) in the end face (44) of said block, an adjustable vent valve (45) in said tapped end portion, said air pressure responsive piston having a skirt portion (68) provided with a guide slot, a guide element (67) secured in said cylindrical air motor housing and extending into said slot, a spring (47) disposed between said other end of said control member (26) and the bottom of said skirt portion and an inlet opening (69) in said cylindrical air motor housing.

References Cited by the Examiner UNITED STATES PATENTS 1,650,377 11/1927 Nixon 54.5 X 2,275,758 3/1942 Harris 60-54.5 X 2,915,016 12/1959 Weaver et al 6054.5 X 3,069,124 12/1962 Roberts 6054.6 X

FOREIGN PATENTS 383,515 11/1932 Great Britain. 798,459 7/ 1958 Great Britain.

EDGAR W. GEOGHEGAN, Primary Examiner.

ROBERT R. BUNEVICH, SAMUEL LEVINE,

Examiners. 

